A wonderful, sunny spring morning - so I decided to check the seagull habitat on our roof before the mating season begins in earnest next month.

Herring gulls (on the endangered list in the UK) nest in profusion on the rooftops of Hastings Old Town, and our house does not escape. Each year we usually have two resident pairs: one nesting between the chimney pots of the bigger, higher chimney, and the other in the roof valley in the lee of the rear chimney. It's this latter that cause the problems.

Two or three years ago, we had a roof leak. As bad luck would have it, the water dripped through the ceiling right onto my sleeping head in the bedroom below. What you might dub a wake-up call. It had been caused by rainwater backing up into the eaves as a result of the build-up of nesting debris in the gully. Since then, I've taken the precaution of climbing up there every year for an inspection.

Herring gulls mate for life and pairs nest and breed annually between April-September in the UK. They typically lay between 2-3 eggs though rarely do three chicks all survive. In between breeding seasons, according to my herring gull bible, the classic study The Herring Gull's World (Niko Tinbergen, 1953), they disperse into winter flocks, perhaps flying inland. In spring, the pairs return to the breeding ground, encountering and recognising each other visually and aurally. My perception, however, is that many of the Hastings birds actually hang around like moody teenagers all winter.

That said, I find on opening the Velux window in the roof which gives me access to the valley that no gulls are yet in residence here. However, a pair ensconced between the pots of the upper chimney start shrieking immediately upon my emergence, setting off answering screams across the Old Town. Meanwhile, three or four flies clustering around the inside of the window within the attic are immediately released.

Although there are no nesting birds here yet, there is evidence of previous activity. The lead-clad gully is clogged with deposited debris. Some obvious seagull acquisitions - fragments of fishermen's ropes and nets, small bones - but mainly a heap of muddy soil. I can't figure out how the birds transport it here, if indeed that is what they do. So I set to work to remove it with brush and shovel, an awkward job, depositing it shovelful by shovelful into the plastic basin inside the attic. Meanwhile, the gulls on the other chimney have soon got used to me, settling down to watch me with their little yellow eyes. And at last the gully is cleared for the free flow of rainwater - for a while.

Soon, the gulls' world will go crazy again. Mating, laying, screaming, shitting, feeding the offspring that grow with alarming speed from tiny fluffy brown balls into gawky, full-size flapping things by the end of August. They mark out our springs and summers with untiring precision.